Seismic performance evaluation of adjacent structures connected with negative stiffness and inerter-based dampers

Abstract

The seismic performance evaluation of two adjacent single-degree-of-freedom structures (SDOF) connected with a novel negative stiffness-inerter-based damper (NSID), tuned inerter damper (TID) and viscous damper (VD) is studied under base excitation. The two SDOF structures are typical of adjacent bridge structures that are vulnerable to pounding during strong seismic activity. The base excitation is modelled as a stationary white noise random process. The equations of motion are written in state space form, and optimal parameters for maximum possible response reduction are evaluated. The optimal parameters are based on minimising the total relative energy of two adjacent structures under white noise base excitations. The optimal parameters obtained for TID and NSID show that adding an inerter to a VD lowers the optimum damping ratio. Also, adding negative stiffness to TID further lowers the optimum inertance and damping ratio. The performance of optimised dampers connecting adjacent SDOF systems is then assessed under real earthquake records. Numerical results indicate that NSID and TID can achieve similar or even better response reduction than VD using a smaller damping coefficient. Among the two connected systems, more flexible ones show higher response reduction. The analytical study demonstrates that the effective damping of viscous dampers can be enhanced by adding the negative stiffness and inerter elements to the dashpot.